<template>
  <div class="particle-background" ref="containerRef"></div>
</template>

<script setup>
import { ref, onMounted, onUnmounted } from 'vue'
import * as THREE from 'three'

const containerRef = ref(null)
let scene, camera, renderer, particles, animationId

onMounted(() => {
  initThree()
  animate()
  handleResize()
  window.addEventListener('resize', handleResize)
})

onUnmounted(() => {
  window.removeEventListener('resize', handleResize)
  if (animationId) {
    cancelAnimationFrame(animationId)
  }
  if (renderer) {
    renderer.dispose()
  }
})

const initThree = () => {
  // 创建场景
  scene = new THREE.Scene()
  
  // 创建相机
  camera = new THREE.PerspectiveCamera(
    75,
    window.innerWidth / window.innerHeight,
    0.1,
    1000
  )
  camera.position.z = 500
  
  // 创建渲染器
  renderer = new THREE.WebGLRenderer({ 
    alpha: true,
    antialias: true
  })
  renderer.setSize(window.innerWidth, window.innerHeight)
  renderer.setClearColor(0x000000, 0)
  containerRef.value.appendChild(renderer.domElement)
  
  // 创建粒子
  createParticles()
}

const createParticles = () => {
  const particleCount = 1000
  const geometry = new THREE.BufferGeometry()
  const positions = new Float32Array(particleCount * 3)
  const colors = new Float32Array(particleCount * 3)
  
  for (let i = 0; i < particleCount * 3; i += 3) {
    // 位置
    positions[i] = (Math.random() - 0.5) * 2000
    positions[i + 1] = (Math.random() - 0.5) * 2000
    positions[i + 2] = (Math.random() - 0.5) * 2000
    
    // 颜色 - 蓝色系科技感
    colors[i] = 0.0 + Math.random() * 0.5     // R
    colors[i + 1] = 0.8 + Math.random() * 0.2 // G  
    colors[i + 2] = 1.0                       // B
  }
  
  geometry.setAttribute('position', new THREE.BufferAttribute(positions, 3))
  geometry.setAttribute('color', new THREE.BufferAttribute(colors, 3))
  
  // 粒子材质
  const material = new THREE.PointsMaterial({
    size: 3,
    vertexColors: true,
    transparent: true,
    opacity: 0.8,
    blending: THREE.AdditiveBlending
  })
  
  particles = new THREE.Points(geometry, material)
  scene.add(particles)
}

const animate = () => {
  animationId = requestAnimationFrame(animate)
  
  if (particles) {
    particles.rotation.x += 0.001
    particles.rotation.y += 0.002
    
    // 让粒子有呼吸效果
    const positions = particles.geometry.attributes.position.array
    for (let i = 0; i < positions.length; i += 3) {
      positions[i + 2] += Math.sin(Date.now() * 0.001 + i) * 0.1
    }
    particles.geometry.attributes.position.needsUpdate = true
  }
  
  renderer.render(scene, camera)
}

const handleResize = () => {
  if (camera && renderer) {
    camera.aspect = window.innerWidth / window.innerHeight
    camera.updateProjectionMatrix()
    renderer.setSize(window.innerWidth, window.innerHeight)
  }
}
</script>

<style scoped>
.particle-background {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
}
</style> 